Natural rubber latex is most useful in the production of dip-formed goods such as gloves, balloons, condoms, dental dams, and tubing. The vulcanized latex films utilized for these applications exhibit useful and desirable mechanical properties. The presence of certain non-rubber components in the latex, however, tends to inhibit these desired properties. Because these non-rubber components are relatively low molecular weight substances--that is, with molecular weights substantially below about 10,000--these components may act undesirably as a dilutent and plasticizer in dried vulcanized films prepared from latex. As a result, a vulcanized film prepared from a latex containing a relatively high content of these low molecular weight non-rubber components may suffer from less desirable mechanical properties as compared with a film prepared from a latex containing a relatively low content of these components.
The low molecular weight non-rubber component content of Hevea brasiliensis (also known as the Brazilian rubber tree) rubber latex is relatively low.
It is well known that Hevea brasiliensis is the preferred source of natural rubber latex, but recent concerns about allergic reactions by some individuals to rubber products made from Hevea brasiliensis rubber latex has motivated work toward other rubber sources. For example, natural rubber latex from the guayule bush and related plants have been used as a Hevea brasiliensis substitute. Guayule latex, however, typically contains a relatively high concentration of low molecular weight non-rubber components that deleteriously impact many of the properties of the latex and dipped formed goods thereof. Because these low molecular weight non-rubber components are non-extractable due to their water insolubility, techniques known heretofore in the art for purifying latex, especially guayule latex, have proven to be unsuccessful in removing the low molecular weight non-rubber components from the latex. Therefore, there is a need in the art for an improved method for purifying latices that contain relatively large concentrations of low molecular weight non-rubber components.